A. Field of the Invention
This invention relates to pressure gauges and particularly to means and methods for advising the pool owner of the condition of the swimming pool filter system and permitting bleed air into the filter system and evacuating air under high pressure from the filter system.
B. Description of the Prior Art
In swimming pools it is necessary to provide a filter system to remove foreign matter from the water thus providing a clean and aesthetically desirable swimming pool. This is accomplished by constructing a filter system remote from the swimming pool and pumping pool water from the pool through the filter system and back into the swimming pool.
The filter system is customarily constructed of a tank which contains a filter element or elements arranged between the pool water inlet and pool water outlet of the tank. The filter element normally comprises either a series of particle screens or accumulations of diatomaceous earth contained within a series of cloth enmeshments. Because of its cost and effectiveness, diatomaceous earth has become the most favored material for use in the filter system. When using diatomaceous earth the tank is normally filled with the diatomaceous earth to a level below the top of the tank.
Swimming pool water normally contains a great deal of air because of the turbulance caused by the use of the swimming pool. In addition, spas also require a filter system and these spas have water which has a high concentration of air bubbles because of the use of high powered jets to direct water into the spa. Consequently, the water entering the filter system of either a swimming pool or a spa is normally laden with air bubbles.
After the air-laden pool water enters the filter system the filter element is useful to remove foreign particles from the pool water and trap the foreign particles, thus permitting only clean water to flow back into the swimming pool. The air bubbles in the pool water are also removed by the filter system and these air bubbles have a tendency to accumulate at the top of the tank above the filter element.
When new the filter element permits the air collected above it to pass back into the filter system and out into the swimming pool after the filter system has been turned off. However, after the filter system has been used for a period of time, the filter element becomes dirty and clogged and prevents the passage of air back into the swimming pool. Thus, air pressure builds within the tank above the filter element. This pressure may be hazardous, because to change the filter element it is necessary to unbolt or otherwise unfasten the top of the tank containing the filter element and remove the filter element from the tank. If the pressure build-up is sufficiently high, the top of the tank may become a projectile and fly off of the tank possibly injuring the pool owner.
It is also desirable to provide a filter system which will indicate to the pool owner the condition of the filter element and advise the pool owner when the filter element needs to be changed.
Under certain operating conditions the filter system may also have a vacuum created within the tank, thus reducing the usability of the filter system. Therefore, it is also desirable to have a pressure gauge which will bleed air into the filter system to prevent the occurence of a vacuum within the filter system.
It is well known that a valve may be provided with a filter system above the filter element to bleed air out of the tank. However, pool owners often forget to open the valve prior to changing the filter element. This situation leads to possible problems as discussed above wherein the top of the tank may become a harmful projectile.
It is also known that pressure gauges may be installed in the filter system to advise the pool owner of the condition of the filter system. However, these pressure gauges do not have the ability to bleed air in and out of the system, thus leaving potential hazards. Furthermore, these pressure gauges are often difficult to read and thus pool owners are often reluctant to do so.